Differential mode interference

Sub -mode interference will in the electrical interference voltages and currents on the connecting lines between electrical components or electrical components understood propagating it in opposite directions.

In contrast to common-mode interference , differential- mode interference is superimposed on the actual useful signals because they propagate in the same direction as the useful signals on the connecting lines.

The analysis and avoidance of these disturbances takes place within the scope of electromagnetic compatibility .

The coupling of push-pull interference in electrical circuits can be caused by inductive coupling ( magnetic fluxes that change over time or neighboring AC lines). Other causes can be the galvanic coupling of several different circuits, which influence each other through common conductor sections, such as a common ground connection . In special cases, common-mode interference can turn into differential-mode interference.

Since push-pull interference propagates in the same direction as the useful signals, there are not the same options as for suppressing common-mode interference. The primary remedy is to avoid or minimize the causes, such as undesired magnetic or galvanic coupling. To reduce inductively coupled push-pull interference in z. B. two-wire cables twisting the cable is very effective.

In those cases in which the interference occupies other frequency ranges than the useful signals, an improvement can be achieved by using appropriate filters . Special examples are line filters , which mostly include filter elements against higher-frequency differential mode interference as well as against common mode interference.

See also: push-pull signal